A disk-shaped merry-go-round of radius 3.03 mand mass 145 kg rotates freely with an angular speed of 0.681 rev/s . A 65.4 kg person running tangential to the rim of the merry-go-round at 3.41 m/s jumps onto its rim and holds on. Before jumping on the merry-go-round, the person was moving in the same direction as the merry-go-round's rim. What is the final angular speed of the merry-go-round?

Respuesta :

Answer:

[tex]\omega_2=0.891\ rev/s[/tex]

Explanation:

Given that

Radius , r= 3.03 m

Mass of disk , M= 145 kg

Initial angular velocity

ω=0.681 rev/s

Mass of person , m= 65.4 kg

Velocity of person , V= 3.41 m/s

Initial mass moment of inertia

[tex]I_1= \dfrac{M\times R^2}{2}[/tex]

[tex]I_1= \dfrac{145\times 3.03^2}{2}=665.61\ kg.m^2[/tex]

Final mass moment of inertia

[tex]I_2= \dfrac{M\times R^2}{2}+m\times R^2[/tex]

[tex]I_2= \dfrac{145\times 3.03^2}{2}+65.4\times 3.03^2=1266.04\ kg.m^2[/tex]

[tex]Final\ angular\ velocity =\omega_2[/tex]

By using angular momentum equation

[tex]I_1\times \omega+m\times V\times R=I_2\times \omega_2[/tex]

[tex]665.61\times 0.681+65.4\times 3.41\times 3.03=1266.04\times \omega_2[/tex]

[tex]1129.01= 1266.04\times \omega_2[/tex]

[tex]\omega_2=\dfrac{1129.01}{1266.04}[/tex]

[tex]\omega_2=0.891\ rev/s[/tex]

Thus the angular velocity will be 0.891 rev/s